PTL 1 discloses a conventional magnetic sensor in which one bias magnet is disposed directly below four magnetoresistance elements. PTL 2 discloses another conventional magnetic sensor in which a bias magnet is disposed to cover a region above a magnetoresistance element. The conventional magnetic sensors can hardly have small sizes and high accuracy.
PTLs 2 to 5 disclose conventional magnetic sensors in which plural magnetoresistance elements are disposed on a board. In each of PTLs 2 to 5, a specific configuration and a specific shape of each of the magnetoresistance elements are not clear. Therefore, PTLs 2 to 5 cannot provide a magnetic sensor having high sensitivity to a magnetic field.